Pneumatic tire



(No Mode.) 2 sheets-sheep 1. J. F. PALMER. PNBUMATIG TIRE.

No. 476,681. Patented June '7, 1892.

WMM/ames Ww p sus ca.. mowmmo.r wnsmnc'mn, n. c,

(N0 Mdel.) 2 Sheets- Sheet 2.

J. E'. PALMER.

PNBUMATIG TIRE.

No. 476,681. Y Patented June 7,1892.

UNrrnD STATES Partnr Ormea.

JOHN F. PALMER, OF RIVERSIDE, ILLINOIS.

PN EU MATIC TIRE.

SPECIFICATION forming part of Letters Patent No. 476,681, dated une 7,1892.

Application filed April 23, 1892. Serial No.430,300. (No model.)

To a/ZZ whom it may concern,.- thickened rubber held against the canvasBeit known that I, JOHN FULLERTON PAL- backing by being molded thereon.In order MER, a citizen of the United States, residing that the rubberthus molded may be formed at Riverside, in the county of Cook and Stateinto a tube, the lateral edges thereof beyond 55 5 of Illinois, haveinvented a new and useful the point Where it is caused to adhere to theImprovement in Pneumatic Tires; and Iherecanvas are continued into iiapsof a length by declare the following to be a full, clear, sufficientwhen joined together attheir edges and exact description thereof. toproduce an inner air-tube of the desired My invention relates to theproduction cfa sectional measurement. The canvas to Which 6o Iopneumatic tire of the kind which are known as the rubber is molded maybe further continhealing,and is in the nature of an improveucd laterallyinto flaps not adhering to the ment upon the pneumatic tire Which formsrubber, said flaps being sewed together with the subject-matter ofLetters Patent No. or Without the interposed reinforcing-piece in467,6i2, granted to me January 26, 1892. As the manner described in mysaid granted Let- 65 r 5 in the case of the tire described in saidLetters Patent.

ters Patent, the purpose of my invention is My invention consists,therefore, in the to provide in the tire, composed mainly of general andin the preferred method of prorubber and containing air under pressure,a ducing the pneumatic tire herein set forth. tread portion of increasedthickness and held, In the drawings, Figure l is a transverse 7o zo asit is called,under compression,butmore sectional View illustrating themethod of moldproperly speaking under contraction, and ing. the rubber'upon the canvas before rethickened, whereby any punctures that mayversing the curvature to produce a compresoccur in the tread portion, asby a pin-point, sion or contraction of the tread portion. Fig.knifebladc, sharp stone, or the like, shall be 2 is a view illustratingthe position of the 75 25 automatically closed and the exhaust of airtube in the act of reversing the curvature; through said puncture shallbe prevented. Fig. 3, a view showing the tube reversed be- Incidentallythe characteristics thus given to fore sealing, and Fig. e a sectionalview oi' a the tire permit the same to be inflated withtire after thesame has been formed into a out the provision of the air-filling tube,the tube. 8O 3o operation being effected by introducing a A representsthe rubber portion of an inner sharp-pointed hollow needle or nozzleeontube for pneumatic wire, and B the canvas- Jell" nected with anair-pump. retaining strip therefcthe oftice of which is My inventionconsists more particularly in particularly to serve as an inelasticbacking an inner tube for a pneumatic tire having its for the treadportion, through the medium of 85 3 5 tread portion made of thickenedrubber and which, on reversal of curvature, the requisite held undercompression by causing the same compression or contraction is effected.As to be curved from a concave to a convex po- Will be observed upon anexamination of Figs. sitionby mechanical manipulation,regardless l and2, the rubber portion A comprises a of the presence or absence ofinternal pnensection a, which is thickened, and two lateral 9o 4c maticpressure, this result being accomplished iiaps a2, which are notthickened, and have by molding the rubber upon a canvas strip theiredges by preference cut out for the purhaving the width substantially ofthe tread pose of joining them together. By preferportion and ofacharacter to be substantially ence, also, the canvas backing isextended nOnstretching and non-lengthening, the canlaterally into dapsb, the edges of which may 95 45 vas and rubber being molded primarilyupon be sevved together in completing the tube. It a curvaturetransversely the reverse of the should be understood,however, that theflaps intended curvature in the iinished tire. It of canvas Z2 may beentirely omitted without is clearly Within my invention, however, todeparting from my invention or in any sense provide for the reversal ofthe curvature lon giaffecting its operaiiveness, their employment Aroo5o tudinally as Well as transversely, the effect being purely arbitrary,

being to give asubstantial compression of the To produce the tire Iproceed as follows:

Upon a ring-shaped mandrel, properly curved in cross-section, the stripof canvas is firmly stretched, and in order to bring about a conformitywith the curvature of the mandrel the canvas may comprise two stripsopposite in their character, each cut on the diagonal,withlongitudinally-diagonal long fibers'and trans-v verselydiagonal shortibers, although it should be understood that any other mode of giving tothe canvas a non-stretching character, coupled with a suitable curvatureto conform to themandrel, may beemployed in its place Without departingfrom my4 invention. In this connection it may be further stated thatcanvas is not the only material which I intend to employ, anysuitablefiexible material having the essentially-requisitecharacteristics beingfcapable'of use without departing from myinvention. The canvas Ahaving been applied to the mandrel with orwithout the iiaps Z), the rubber portionof the inner tube lis thereuponmolded i upon the mandrel carrying thecanvas,asdescribed: The treadportion of `the rubber is thickened;l and it is found in some casesconvenient to mold thev thickened portion and the flap portionseparately-that is to say-,first to mold the rubber with the thicknessof the iiap portion and in a continuous strip from edge to edge, andafterward to mold on the tread portion a further strip of the widthintended to give to the tread portion an increased thickness. It is tobe understood that it is usually found desirable to mold the rubberbefore vulcanization, supplying it with the requisite vulcanizingingredients, and after it has been molded upon the mandrel in the mannerdescribed it is subjected to the proper heat, tbc., for producingvulcanization. One effect of vulcan'- ization is to produce an intimatecohesion between the canvas backing and the tread portion of the tire onthe under face thereof or that adjacent to the mandrel. Aftervulcanization the canvas and the rubber secured thereto are withdrawnfrom the Inandrel andthe curvature reversed in the manner illustratedinl Figs. l, 2, and 3, so that whereas the canvas when on the mandrelwas between'the rubber and the center of the ring it has become changedto a position where the rubber shall be between the canvas and thecenter of the ring, the canvas in this operation being changed from aconcave to a convex form in cross-section and the thickened or treadportion of the tube being caused to have a reverse curvature tocorrespond. It is not deemed absolutely requisite that a perfect curvein cross-section shall be produced, as it is found that a change from aconcave to a very slightly convex or approximately flat conditionVproduces a desirable result in the inished product. It is merelyessential that such a change in the curvature of the canvas incross-section, and hence the curvature of the thickened rubber, shall beeifected as will bring about a substantial compression or contraction ofthe thickened rubber. The curvature being effected as described, thefree ends of the flaps a2 of rubber are joined together by a suitablecement, the strength of the joint being materially increased by theouter envelope of canvas generally employed with tires of this nature.

For the purpose of infiating the tire the point of a syringe-pump may beinserted through the tread portion and air thus forced in. When thepoint is Withdrawn, the normal tendency given to the rubber by thecompression eected under the influence of the curvature of the canvasserves automatically to close the puncture and prevent the air fromexhausting. Any small aperture that may occur in the tire at thetreadportion is automatically closed forthe same reason.

It is to be noted that the characteristic quality thus given to thetread portion is present regardless of the fact Whether air undercompression is introduced into the'tube or not. In referring to air asthe tube-inflating-medium it is to be understood that I intend to coversteam` gas, water, or any fluid that may be available as a substitutefor air, and the term rubber is intended to cover the genus ofWhich'rubber is the best-known eX- ample.

"What I claim as new, and desire to secure by-Letters Patent, is-

l. An inner tube for a pneumatic tire for bicycles, dro., having thetread portion of increased thickness held normally under .compression,as described, and having at its hub side a continuous sealed joint,substantially as described.

2. The method of producing an inner tube for pneumatic tires, whichconsists in molding the rubber therefor with a thickened tread portionon a reverse curvature, causing to adhere to the concave face asubstantially non-stretching flexible material, reversing the curvatureof the tread portion and nonstretching backing, and finally joining theIOO IIOv

flaps and sealing the same, substantially as described.

3. The method of producing an inner tube for pneumatic tubes, whichconsists, first, in applying to an annular mandrel having the propercurvature, a curved ynon-stretching annular strip of iiexible material,molding upon said mandrel a strip of rubber having its edges unjoined,thickening the rubber on the outer side of the mandrel or form,vulcanizing the parts together, and thereupon reversing the curvature ofthe ilexible material and thickened portion of the rubber, and joiningand sealing the edges of the strip to form the air-tube, substantiallyas described.

In testimony whereof I affix my signature, in presence of two witnesses,this 19th day of Api-i1, A. D. 1892.

JGHN F. PALMER. Vitnesses:

J. Ross CoLHoUN, DOUGLAS DYRENFORTH.

